Ms Ardern found out about the pregnancy last October and told Mr Gayford about the news through Facebook video call. The couple announced the pregnancy to the public on 19 January.

Last Monday, Ms Ardern was advised not to fly any more and since then had been working from home in Auckland, rather than travelling to Wellington. Mr Peters carried out some of the prime minister's Wellington-based duties this week, chairing Cabinet and hosted Ms Ardern's weekly post-cabinet media conference.

Yesterday Clarke Gayford tweeted a photo of the prime minister still working at home.

There won't be any more formal announcements from the Prime Minister's Office until Ms Ardern and Mr Gayford announce the birth - likely on social media. The couple have yet to reveal the baby's gender, but Ms Ardern was gifted the name Waru at Ratana celebrations and the name Waimirirangi was offered at Waitangi Day celebrations if the baby was a girl.

If the prime minister's baby is born today he or she will share a birthday with Pakistan's former Prime Minister Benazir Bhutto, who is the only other elected leader to have given birth while in the role.

The much-anticipated arrival has gone global, as international media outlets keep track of what is unfolding at Auckland Hospital.

The New York Times reports Ms Ardern's pregnancy has prompted a national conversation about working mothers.